Field of the Invention
The present invention relates to an electrophotographic photosensitive member, a process cartridge and an electrophotographic apparatus.
Description of the Related Art
Since an electrical external force and a mechanical external force for charging and cleaning are applied to a surface of an electrophotographic photosensitive member, the electrophotographic photosensitive member is required to have durability (such as wear resistance) against such external force.
In order to meet such a requirement, an improvement technique of using, in a surface layer of an electrophotographic photosensitive member, a resin having high wear resistance (such as a curable resin) has been conventionally employed.
On the other hand, an example of a problem occurring because of the increased wear resistance of a surface of the electrophotographic photosensitive member includes degradation of cleaning performance.
As a technique for improving the cleaning performance, Japanese Patent Application Laid-Open No. 2010-26240 discloses an electrophotographic photosensitive member having a specific concave portion on a surface thereof.
Japanese Patent Application Laid-Open No. 2010-250355 discloses a toner image carrier having a specific concave portion on an outer peripheral surface thereof.
Even when the techniques disclosed in Japanese Patent Application Laid-Open No. 2010-26240 and Japanese Patent Application Laid-Open No. 2010-250355 are employed, however, although the cleaning performance can be improved, there still remains room for improvement because a streak-like image defect (hereinafter also referred to as the “H/H initial streak (high temperature/high humidity environmental initial streak)”) is caused on a halftone image having a density of about 30% output after printing in a low printing mode is performed under a high-temperature and high-humidity environment.